Dressing tool and method for the production thereof

ABSTRACT

The invention relates to a dressing tool, comprising a main body ( 2 ), the working surface ( 6 ) of which is covered with hard-material grains ( 7 ) distributed on the main body ( 2 ). According to the invention, recesses ( 8 ) for accommodating the hard-material grains ( 7 ) are created in the main body ( 2 ), wherein the recesses are then filled with an adhesive, the excess adhesive is removed across the main body ( 2 ), and thereafter the hard-material grains ( 7 ) are flung onto the main body ( 2 ), so that only the grains ( 7 ) located in the recesses ( 8 ) remain adherent to the working surface of the tool. Said hard-material grains can then be bonded to the main body by means of a physical and/or chemical bond. Thus, a distribution of the grains over the working surface of the tool that can be precisely defined in advance is ensured.

The invention relates to a dressing tool which comprises a main body with a working surface and hard-material grains distributed over this working surface.

This type of tool is disclosed in publication EP-A-2 535 145. The tool described here is used in particular for dressing grinding discs and worm grinding wheels for grinding toothed wheels and similar components. In the method of producing the tool an adhesive is first of all applied to the working surface of the tool to be produced with a defined film thickness and the hard-material grains are then applied to the working surface provided with the adhesive and remain permanently bonded here as a particle covering after the adhesive has cured.

This known method makes it possible to cover the main body quickly with the particles provided for this purpose, but not to provide a perfectly even distribution density of the hard-material grains over the working surface of the tool. This can have a negative impact upon the quality of the grinding effect that can be achieved with the tool.

The object underlying the invention is to devise a dressing tool and a method for the production thereof in which the main body of the tool is covered with improved distribution of the hard-material grains, and so with this tool optimisation of its working surface as regards its grinding effect is achieved.

According to the invention this object is achieved by recesses being created in the main body in order to accommodate the hard-material grains, the geometry of which is adapted to that of the hard-material grains. In this way, the particles accommodated in the recesses are individually positioned precisely, i.e. according to the arrangement and distribution over the recesses on the working surface of the tool. The hard-material grains can thus be applied with a defined distribution density by the recesses accommodating them being created appropriately distributed over the working surface of the tool.

A distribution density that is particularly advantageous in practice is produced by an arrangement of the recesses which results in a specific spacing of the hard-material grains relative to their insides in relation to the grain size in the finished tool.

It can also often be advantageous if the recesses, in relation to the central axis of the tool, are created more densely distributed on the outside than on the inside.

The recesses according to the invention are generally dimensioned and configured such that they can each accommodate one hard-material grain. However, within the framework of the invention it is also possible to dimension and configure the recesses depending on the grain size and/or shape of the particles such that they can each accommodate more than just one grain.

According to the invention the recesses are created in the main body by drilling into or stamping the latter. Since the main body is normally metallic, both production methods can be used without any great expenditure relating to apparatus. Depending on the composition of the main body, other production methods, such as for example laser-operated methods, can however in principle also be used.

Furthermore, the invention makes provision such that the recesses created in the main body are filled with a preferably electrically conductive adhesive, the excess adhesive being removed across the main body and thereafter the hard-material grains being flung onto the main body. In this way it is ensured that only the particles located in the recesses remain adherent to the working surface of the tool.

The invention also makes provision such that the particle covering that is produced is then galvanically nickel-plated, the layer of nickel being deposited over the adhesive and the hard-material grains being surrounded by the nickel bond. They thus remain entirely enclosed in the recesses up to a specific grain height, physical and/or chemical bonds, such as for example a nickel or solder bond, also supporting the retention of the particles in the desired direction. Within this context it is advantageous if the recesses in the main body are configured and dimensioned such that in this way a certain orientation of the hard-material grains preferably in the form of dodecahedrons is brought about.

Advantageously, the recesses are dimensioned and configured such that they can accommodate hard-material grains with a consistent grain shape and/or grain size.

In the following the invention will be described in more detail by means of an exemplary embodiment with reference to the drawings. These show as follows:

FIG. 1 is a dressing tool comprising a main body, illustrated in simplified form and slightly perspectively,

FIG. 2 is a view of a partial region of the working surface of the dressing tool according to FIG. 1;

FIG. 3 is a single hard-material grain of the working surface according to FIG. 1, shown perspectively,

FIG. 4 is an outline of this hard-material grain according to FIG. 3, and

FIG. 5 is a section along line A-A according to FIG. 4.

The dressing tool shown in FIG. 1 serves to dress the edges of worm grinding wheels that are used, for example, to grind correspondingly formed toothed wheels. These dressing tools can have one or a number of these main bodies 2 with a corresponding number of working surfaces 6. These working surfaces can also be provided with special profile shapes and in addition the dressing tools can be produced as dressing toothed wheels.

The dressing tool 1 consists of a main body 2 with a cylindrical shaft 3 that can be coupled to a rotary drive in order to drive the main body 2 that can be rotated about the axis 4. The edges 5 of the main body form the working surfaces 6 of the tool. For this purpose they are provided with a covering of hard-material grains 7.

A partial region of the covering is shown greatly enlarged in FIG. 2. In the exemplary embodiment described, the hard-material grains 7 embedded by a nickel bond 9 are provided as diamond grains with a grain diameter of, for example, 400 μm and a preferably dodecahedral form. Depending on the conditions of use, other grain shapes and sizes and other materials, such as super-abrasive or similar highly abrasive materials can of course also be used.

As can be seen in detail from FIG. 3 to FIG. 5, according to the invention recesses 8 arranged with precisely defined distribution are created in the main body 2, the form and dimensions of which are adapted to those of the hard-material grains 7 so that they can accommodate grains with more or less form-fit up to a certain grain height. On the basis of their particular configuration, they are also able to give the hard-material grains 7 the alignment which is optimal for the respective function of the tool. Thus, the depth T of the respective recess and also the projecting height H of the grain can be determined, and so the parameters can be configured appropriately for optimal dressing and a maximum life span of the tool.

The recesses 8 are preferably either drilled, stamped and/or lasered into the main body 2, depending on from which material the normally metal main body 2 is produced. The distribution density of the recesses 8 over the working surface 6 of the tool is chosen so that in the finished tool the distances between the grains 7 on the inside are for example approximately half the grain size D, in the exemplary embodiment described these distances being consistent in both the horizontal and in the vertical direction.

Depending on the composition of the grains and/or functioning of the tool it is of course possible to vary the distribution density of the recesses and so that of the grain covering over the whole surface, or also from zone to zone. In the latter case the recesses 8 are distributed more densely on the outside in relation to the central axis 4 of the tool than applied to the inside so that with the finished tool the latter is provided with more hard-material grains per unit area on the outside than on the inside because in the normal case the grains lying on the outside are in use first, and so for a longer time than the particles lying on the inside.

After applying the recesses 8 to the working surfaces 6 of the main body they are filled with an electrically conductive adhesive, and the excess adhesive is then removed over the main body 2, for example with a doctor blade. Then the diamond grains 7 are flung onto the working surface 6, the grains only remaining adherent in the recesses 8 filled with adhesive. By means of a corresponding arrangement of the recesses the grain distribution over the working surface 6 can be varied in many ways. In this way precisely defined distribution of the grains over the working surface of the tool is always produced.

The design according to the invention of the tool thus basically has the advantage that it guarantees positioning of the hard-material grains over the working surface of the tool that can be specified precisely in advance. By appropriate specification of this value the tool can be improved such that it is optimal for the respective application.

The diamond covering produced can then be galvanically nickel-plated. In this case the adhesive for the diamond grains is chosen so that it is compatible with the chemicals of the subsequent galvanic process. Since the adhesive used is electrically conductive, the nickel layer can be deposited on it without any problem so that the diamond grains adhered in the recesses are enclosed neatly by the nickel bond. In this way the edges of the recesses are sealed and the diamond grains are retained better.

The exemplary embodiment described above relates to a main body for dressing tools that are intended in particular for dressing worm grinding wheels. The invention can be used as mentioned above, but also obviously with tools that work in a similar manner, such as for example grinding or honing tools. 

1. A dressing tool which comprises a main body (2) with a working surface (6) and hard-material grains (7) distributed over this working surface, characterised in that a number of recesses (8) produced distances apart from one another are incorporated into the main body (2), in which recesses hard-material grains (7) are accommodated.
 2. The dressing tool according to claim 1, characterised in that a specific number of recesses (8) produced defined distances apart from another are incorporated into the main body (2), in which recesses hard-material grains (7) are accommodated.
 3. The dressing tool according to claim 1, wherein the geometry of the recesses (8) is adapted to that of the hard-material grains (7) so that the hard-material grains (7) are respectively held therein with more or less form-fit.
 4. The dressing tool according to claim 1, wherein the distribution density of the recesses (8) over the working surface (6) of the main body (2) is specified such that the distances between the hard-material grains (7) correspond approximately in proportion to the grain size (D).
 5. The dressing tool according to claim 1, wherein the recesses (8) are created in relation to the central axis (4) of the tool differently on the outside than on the inside.
 6. The dressing tool according to claim 1, wherein the recesses (8) are drilled, stamped and/or lasered into the main body (2).
 7. The dressing tool according to claim 1, wherein the recesses (8) are dimensioned so that they enable specific orientation of the hard-material grains (7) preferably in the form of dodecahedrons.
 8. The dressing tool according to claim 1, wherein the recesses (8) are dimensioned so that they enable the use of hard-material grains (7) with a consistent grain shape and grain size.
 9. A method for the production of a dressing tool according claim 1, wherein the hard-material grains (7) are adhered onto the main body (2) by the recesses (8) being filled with a preferably electrically conductive adhesive, the excess adhesive being removed over the main body (2) with a suitable tool and the hard-material grains (7) then being applied to the main body (2).
 10. The method according to claim 9, characterised in that the grain covering is then provided with a physical and/or chemical bond, such as for example a nickel or solder bond, the nickel layer being deposited on the adhesive, and so the hard-material grains (7) being completely enclosed by the nickel bond (9).
 11. The dressing tool according to claim 2, wherein the geometry of the recesses is adapted to that of the hard-material grains so that the hard-material grains are respectively held therein with a form-fit.
 12. The dressing tool according to claim 2, wherein the distribution density of the recesses over the working surface of the main body is specified such that the distances between the hard-material grains correspond approximately in proportion to the grain size.
 13. The dressing tool according to claim 3, wherein the distribution density of the recesses over the working surface of the main body is specified such that the distances between the hard-material grains correspond approximately in proportion to the grain size.
 14. The dressing tool according to claim 2, wherein the recesses are created in relation to the central axis of the tool differently on the outside than on the inside.
 15. The dressing tool according to claim 3, wherein the recesses are created in relation to the central axis of the tool differently on the outside than on the inside.
 16. The dressing tool according to claim 4, wherein the recesses are created in relation to the central axis of the tool differently on the outside than on the inside.
 17. The dressing tool according to claim 2, wherein the recesses are dimensioned so that they enable specific orientation of the hard-material grains.
 18. The dressing tool according to claim 2, wherein the recesses are dimensioned so that they enable specific orientation of the hard-material grains in the form of dodecahedrons.
 19. The dressing tool according to claim 2, wherein the recesses are dimensioned so that they enable the use of hard-material grains with a consistent grain shape and grain size.
 20. The dressing tool according to claim 3, wherein the recesses are dimensioned so that they enable the use of hard-material grains with a consistent grain shape and grain size. 